Long Island is fighting an epidemic of zombie houses.

Karen Newman started noticing houses in her Levittown neighborhood with large red squares posted on them in early 2014.

Some signs included an X or a slash through them. They reminded Newman, 50, a retired NYPD crime scene photographer, of signs warning emergency responders about unsafe homes in the city. The postings in Levittown by Hempstead Town officials serve the same purpose -- identifying abandoned, neglected properties that have deteriorated to the point of being unsafe.

Newman started taking photos of neglected homes, posting them on a Facebook page she created called "The Levittown Project." She has more than 60 vacant houses on the site.

Levittown, created in the late 1940s as America's first suburb with tidy houses and yards for growing postwar families, is home to 81 zombie houses, according to RealtyTrac, a California firm that tracks the homes that are in the foreclosure process but abandoned. The number in Levittown is the seventh highest among 67 Nassau County ZIP codes.

Newman, a 16-year resident, said that "never in a million years" would she have imagined there would be so many abandoned homes in Levittown. "If you had told me that there would be [safety warning] signs outside houses that have been abandoned, I never would have believed it."

The impact from neglected homes spreads beyond property lines. From scurrying rats and marauding raccoons to the stench of garbage and mold, the quality of neighborhood life is compromised. And the longer the house is abandoned, the worse the problem gets.

"When you see a rat that's the size of a cat on your property, you get scared," said Ora Scheine, 63. She and her husband, Ed, 65, have lived next to a boarded-up house in Dix Hills for seven years. There's a hole in the roof and a tree growing through the chimney. Raccoons frequently roam onto the Scheines' property and knock down their trash pails. "Every day I'm cleaning up garbage on the driveway," she said.

Porzia DiGiorgio, 42, and her husband, John, 44, live on the same cul-de-sac as the Scheines. "You can't even have a friend drive down the street and not make assumptions about your neighborhood," John DiGiorgio said.

Douglas Bunge, 66, said the abandoned home on his Bay Shore block has broken windows and graffiti as well as construction debris and a boat rotting in the backyard -- across the street from an elementary school.

"Lately it has become a real hangout at night for the kids," he said of the empty house. "Somebody could very easily get hurt, there's so much debris over there."

And if someone does get hurt in a crumbling, abandoned house, first responders may be limited in what they can do.

"When a kid roams in to explore and falls through to the basement and gets hurt, how do we get in there?" said Mastic Beach Fire Marshal Carlo Grover. Abandoned homes "are a safety issue and definitely a concern."

Once a month, Grover drives around the village looking for unsafe, abandoned houses that had been reported by residents. He surveys the home from the outside, checking for decaying wood or holes in the roof. Then he peeks through the windows looking for squatters as well as animals, rodents or anything else that could pose a safety threat. Next, he slowly enters while tapping a pole to test the stability of the floor ahead of him.

"If it looks too dangerous, we don't go in," he said. "These abandoned homes aren't just a risk to the public, they are a risk to the department."

Insp. Gerard Gigante, Suffolk Police First Precinct commanding officer, said squatters in abandoned homes often remove valuable copper pipes, causing flooding. Propane tanks and barbecue grills are brought inside for heat and create a fire hazard. He cited one home where stairs had been removed and another where the toilet flushed directly into the basement because the plumbing had been disconnected.

Abandoned homes that sit vacant for months or years can bring another menace to neighborhoods: mold.

"It's a quality-of-life issue for every single neighbor who walks by that house, lives next door to that house, leaves their window open . . . it's a problem in your house then," said Terence McSweeney, a North Babylon civic leader who estimates that a 10th of his community's homes are abandoned.

"It's extremely frustrating," he said. "I grew up in this neighborhood. There was never a vacant house. Last year we had dozens."

Central Islip homeowner Mauricio Turcios, 35, said his community has so many abandoned homes that he doesn't allow his children to play outside. "The bus picks them up and drops them off and that's it," he said, noting that the empty houses have attracted squatters.

Residents who live near abandoned houses said they've spent years calling and sending letters to every official and agency they can find -- all the way up to the federal level. They have tried to track down banks and property owners. But the efforts have amounted to nothing, they said, as the homes and their quality of life decay.

"The great frustration is that every single agency, every entity we've talked to . . . no one can give us any information as to how this can be resolved, when it will be resolved, if it will be resolved," said Pamela Ubl, 61, who has lived near an abandoned home for more than a decade in Bay Shore.

Blame usually first falls on town and village officials, even as those leaders explain to residents that private property laws limit what they can do.

"If our elected officials ultimately are saying they can do nothing, then where do you go?" Ubl said. "Even though we get great expressions of sympathy from our elected officials and the banks involved, we don't want to hear that anymore. We want it resolved."

In Mastic Beach, where the mayor estimates there are hundreds of abandoned homes, residents have tried to rein in the neglect by cutting grass and trimming trees on blighted properties themselves.

In Islip Town, which has three of the ZIP codes with the highest numbers of zombie homes in New York, state Sen. Tom Croci (R-Sayville), the former town supervisor, said the quality-of-life issues brought to officials about abandoned houses "have been overwhelming."

Hempstead Supervisor Kate Murray said it frustrates her as much as any resident to see a house fall into disrepair. "Because the bottom line is we want to help our constituents and want to make sure our neighborhoods stay as beautiful as they can," she said.

Newman said that if anyone visits her Levittown home, no matter which direction they come from, they will see blight -- from shattered windows to tattered porch screens and padlocked doors. "It's just sad because on my block, it's a really beautiful block," she said. "Now looking forward you have to figure, how much is that devaluing my house?"

Annette Melchers, 69, got the answer to that question when she tried to sell her Dix Hills house and buyers were deterred by the property next door -- the same eyesore that worries the Scheines and DiGiorgios.

Impact on neighborhood

Melchers has owned her home for 40 years and lives with her two adult disabled sons, she said. She retired from her job as a nurse practitioner at Sagamore Children's Psychiatric Center three years ago and wants to move to Florida. In 2013 she put her home, appraised at $695,000, on the market.

"The house is terrific, the house is priced right and I get calls on it constantly," said Melchers' real estate agent, Sheila Gatto of Realty Connect USA in Woodbury. "But the minute anyone comes, they look next door to that blighted house and they're afraid."

Gatto said she took about 60 to 70 people to see Melchers' house. Some took one look at the boarded-up home next door and turned right around, she said.

"You can't say to them well maybe the house will be torn down, maybe this, maybe that," Gatto said. "Especially when someone is spending a half-million dollars."

A prospective buyer offered Melchers $550,000 and she was inclined to accept the offer. But he came back with his wife, who refused to even step inside the home.

"I couldn't give this house away because of that house next door," Melchers said. "I feel trapped."

Neighborhood residents said the blighted house is "beyond repair" and all of the copper piping has been ripped out. Even though the home has been boarded up, the front door is unlocked and can be pushed open, requiring constant vigilance by neighbors to ensure no one illegally moves in.

Huntington Town spokesman A.J. Carter said an engineer inspected the house in December. He recommended in his report that it be demolished, noting that it contains a "hazardous environment" of moisture and mold, and recommending the town "clean the concrete foundation walls and slab, and fence-in the concrete foundation for the safety of the public." An administrative hearing on the demolition is scheduled for next month, Carter said.

State Attorney General Eric T. Schneiderman called residents like Melchers "the worst victims" of the zombie home crisis.

"If you work hard and you're working multiple jobs, you manage to save your home after the collapse of the housing market and you're staying current on your mortgage but you've got two abandoned properties around you . . . your opportunity to sell the home and move on is hurt, the property values go down," he said. "It's well documented that crime and vandalism go up. So it brings down a whole community."

Dilapidated abandoned homes have cost Long Island at least $295 million in depreciated home values, according to an analysis of RealtyTrac's zombie home data by Manhattan-based appraisal firm Miller Samuel. Vacant homes are likely to suffer an average price reduction of roughly 20 percent and the five closest neighbors face a price cut of about 5 percent, estimated company chief executive Jonathan Miller, who analyzed the data for Newsday.

Town and village officials said banks could prevent the loss in property values by maintaining an empty home while it is in the foreclosure process.

"If you just put a little money into this house, it would sell for more, it would sell for the asking price in the neighborhood," said Shanna Smith, president and chief executive of the Washington, D.C.-based National Fair Housing Alliance, a consortium of groups focused on ending housing discrimination. Instead, financial institutions "are pulling down the property values and as a result if you live in that neighborhood you can't refinance because you have a hard time . . . getting a line of credit, or your line of credit may be reduced," Smith said.

Those who live near blighted homes lament the lost promise of suburban life that had enticed families to move to Long Island.

"The suburbs have traditionally represented and been emblematic of the American dream," Ubl said. "This is where people came to start their lives and have their children and enjoy a quality of life that they associated with being a middle-class American or a working-class American and to have that undermined . . . I think a lot of people are deeply frustrated and confused and feeling very powerless."